The present invention relates to improved cleaning compositions composed of fluorochlorohydrocarbons selected from the group consisting of the dichlorotrifluoroethanes in admixture with alkanols, to the use of such cleaning compositions, and to methods for cleaning surfaces of articles using such compositions.
Very stringent requirements must be met by solvents used for cleaning purposes. Such solvents should have a relatively low boiling point, be non-flammable and substantially non-toxic and have a high solvent power for the impurities which are to be removed. However, as a rule, these requirements can not be met by a single, pure solvent. A large number of solvent mixtures having more or less widely differing compositions are therefore used in practice. Thus, besides using pure chlorinated and/or fluorinated hydrocarbons for industrial cleaning methods or for vapor degreasing, it is also generally known to use mixtures of fluorochlorohydrocarbons (as the principal solvent) with a co-solvent. Such mixtures can be either non-azeotropic or azeotropic or also azeotrope-like. As used herein, the term "azeotrope-like" indicates that a mixture has an essentially constant boiling point (variation of the boiling point by not more than 5.degree. C.) over a fairly wide concentration range and therefore exhibits behavior similar to that of an azeotrope when used in practice.
Although many efforts have already been made in order to obtain cleaning compositions having the desired properties for various fields of use, the known mixtures still need improvement with regard to their technological, toxicological and environmental properties. Thus, for example as a result of further technical developments in the field of fluxes, new requirements have arisen for improved cleaning compositions which can remove newly developed fluxes. These requirements are not always met, or frequently are only met unsatisfactorily, by the known solvent mixtures. Other known solvent mixtures are multicomponent systems which have complicated compositions (for example, which require three or more essential solvent constituents) or contain major proportions of solvents which are objectionable for toxicological and/or safety reasons (low boiling point, low flash point). In the case of yet other solvent constituents, it is desirable for environmental reasons to replace them with other solvents which are at least equally suitable for the particular applications. Even today, there is therefore still a great need for new solvent mixtures which have new special properties, and which also are more acceptable from the toxicological and environmental points of view.